[linux-2.6-block.git] / fs / nfs_common / nfsacl.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * fs/nfs_common/nfsacl.c
 *
 *  Copyright (C) 2002-2003 Andreas Gruenbacher <agruen@suse.de>
 */

/*
 * The Solaris nfsacl protocol represents some ACLs slightly differently
 * than POSIX 1003.1e draft 17 does (and we do):
 *
 *  - Minimal ACLs always have an ACL_MASK entry, so they have
 *    four instead of three entries.
 *  - The ACL_MASK entry in such minimal ACLs always has the same
 *    permissions as the ACL_GROUP_OBJ entry. (In extended ACLs
 *    the ACL_MASK and ACL_GROUP_OBJ entries may differ.)
 *  - The identifier fields of the ACL_USER_OBJ and ACL_GROUP_OBJ
 *    entries contain the identifiers of the owner and owning group.
 *    (In POSIX ACLs we always set them to ACL_UNDEFINED_ID).
 *  - ACL entries in the kernel are kept sorted in ascending order
 *    of (e_tag, e_id). Solaris ACLs are unsorted.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/gfp.h>
#include <linux/sunrpc/xdr.h>
#include <linux/nfsacl.h>
#include <linux/nfs3.h>
#include <linux/sort.h>

MODULE_DESCRIPTION("NFS ACL support");
MODULE_LICENSE("GPL");

struct nfsacl_encode_desc {
	struct xdr_array2_desc desc;
	unsigned int count;
	struct posix_acl *acl;
	int typeflag;
	kuid_t uid;
	kgid_t gid;
};

struct nfsacl_simple_acl {
	struct posix_acl_hdr acl;
	struct posix_acl_entry ace[4];
};

static int
xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem)
{
	struct nfsacl_encode_desc *nfsacl_desc =
		(struct nfsacl_encode_desc *) desc;
	__be32 *p = elem;

	struct posix_acl_entry *entry =
		&nfsacl_desc->acl->a_entries[nfsacl_desc->count++];

	*p++ = htonl(entry->e_tag | nfsacl_desc->typeflag);
	switch(entry->e_tag) {
		case ACL_USER_OBJ:
			*p++ = htonl(from_kuid(&init_user_ns, nfsacl_desc->uid));
			break;
		case ACL_GROUP_OBJ:
			*p++ = htonl(from_kgid(&init_user_ns, nfsacl_desc->gid));
			break;
		case ACL_USER:
			*p++ = htonl(from_kuid(&init_user_ns, entry->e_uid));
			break;
		case ACL_GROUP:
			*p++ = htonl(from_kgid(&init_user_ns, entry->e_gid));
			break;
		default:  /* Solaris depends on that! */
			*p++ = 0;
			break;
	}
	*p++ = htonl(entry->e_perm & S_IRWXO);
	return 0;
}

/**
 * nfsacl_encode - Encode an NFSv3 ACL
 *
 * @buf: destination xdr_buf to contain XDR encoded ACL
 * @base: byte offset in xdr_buf where XDR'd ACL begins
 * @inode: inode of file whose ACL this is
 * @acl: posix_acl to encode
 * @encode_entries: whether to encode ACEs as well
 * @typeflag: ACL type: NFS_ACL_DEFAULT or zero
 *
 * Returns size of encoded ACL in bytes or a negative errno value.
 */
int nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
		  struct posix_acl *acl, int encode_entries, int typeflag)
{
	int entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
	struct nfsacl_encode_desc nfsacl_desc = {
		.desc = {
			.elem_size = 12,
			.array_len = encode_entries ? entries : 0,
			.xcode = xdr_nfsace_encode,
		},
		.acl = acl,
		.typeflag = typeflag,
		.uid = inode->i_uid,
		.gid = inode->i_gid,
	};
	struct nfsacl_simple_acl aclbuf;
	int err;

	if (entries > NFS_ACL_MAX_ENTRIES ||
	    xdr_encode_word(buf, base, entries))
		return -EINVAL;
	if (encode_entries && acl && acl->a_count == 3) {
		struct posix_acl *acl2 =
			container_of(&aclbuf.acl, struct posix_acl, hdr);

		/* Avoid the use of posix_acl_alloc().  nfsacl_encode() is
		 * invoked in contexts where a memory allocation failure is
		 * fatal.  Fortunately this fake ACL is small enough to
		 * construct on the stack. */
		posix_acl_init(acl2, 4);

		/* Insert entries in canonical order: other orders seem
		 to confuse Solaris VxFS. */
		acl2->a_entries[0] = acl->a_entries[0];  /* ACL_USER_OBJ */
		acl2->a_entries[1] = acl->a_entries[1];  /* ACL_GROUP_OBJ */
		acl2->a_entries[2] = acl->a_entries[1];  /* ACL_MASK */
		acl2->a_entries[2].e_tag = ACL_MASK;
		acl2->a_entries[3] = acl->a_entries[2];  /* ACL_OTHER */
		nfsacl_desc.acl = acl2;
	}
	err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc);
	if (!err)
		err = 8 + nfsacl_desc.desc.elem_size *
			  nfsacl_desc.desc.array_len;
	return err;
}
EXPORT_SYMBOL_GPL(nfsacl_encode);

/**
 * nfs_stream_encode_acl - Encode an NFSv3 ACL
 *
 * @xdr: an xdr_stream positioned to receive an encoded ACL
 * @inode: inode of file whose ACL this is
 * @acl: posix_acl to encode
 * @encode_entries: whether to encode ACEs as well
 * @typeflag: ACL type: NFS_ACL_DEFAULT or zero
 *
 * Return values:
 *   %false: The ACL could not be encoded
 *   %true: @xdr is advanced to the next available position
 */
bool nfs_stream_encode_acl(struct xdr_stream *xdr, struct inode *inode,
			   struct posix_acl *acl, int encode_entries,
			   int typeflag)
{
	const size_t elem_size = XDR_UNIT * 3;
	u32 entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
	struct nfsacl_encode_desc nfsacl_desc = {
		.desc = {
			.elem_size = elem_size,
			.array_len = encode_entries ? entries : 0,
			.xcode = xdr_nfsace_encode,
		},
		.acl = acl,
		.typeflag = typeflag,
		.uid = inode->i_uid,
		.gid = inode->i_gid,
	};
	struct nfsacl_simple_acl aclbuf;
	unsigned int base;
	int err;

	if (entries > NFS_ACL_MAX_ENTRIES)
		return false;
	if (xdr_stream_encode_u32(xdr, entries) < 0)
		return false;

	if (encode_entries && acl && acl->a_count == 3) {
		struct posix_acl *acl2 =
			container_of(&aclbuf.acl, struct posix_acl, hdr);

		/* Avoid the use of posix_acl_alloc().  nfsacl_encode() is
		 * invoked in contexts where a memory allocation failure is
		 * fatal.  Fortunately this fake ACL is small enough to
		 * construct on the stack. */
		posix_acl_init(acl2, 4);

		/* Insert entries in canonical order: other orders seem
		 to confuse Solaris VxFS. */
		acl2->a_entries[0] = acl->a_entries[0];  /* ACL_USER_OBJ */
		acl2->a_entries[1] = acl->a_entries[1];  /* ACL_GROUP_OBJ */
		acl2->a_entries[2] = acl->a_entries[1];  /* ACL_MASK */
		acl2->a_entries[2].e_tag = ACL_MASK;
		acl2->a_entries[3] = acl->a_entries[2];  /* ACL_OTHER */
		nfsacl_desc.acl = acl2;
	}

	base = xdr_stream_pos(xdr);
	if (!xdr_reserve_space(xdr, XDR_UNIT +
			       elem_size * nfsacl_desc.desc.array_len))
		return false;
	err = xdr_encode_array2(xdr->buf, base, &nfsacl_desc.desc);
	if (err)
		return false;

	return true;
}
EXPORT_SYMBOL_GPL(nfs_stream_encode_acl);


struct nfsacl_decode_desc {
	struct xdr_array2_desc desc;
	unsigned int count;
	struct posix_acl *acl;
};

static int
xdr_nfsace_decode(struct xdr_array2_desc *desc, void *elem)
{
	struct nfsacl_decode_desc *nfsacl_desc =
		(struct nfsacl_decode_desc *) desc;
	__be32 *p = elem;
	struct posix_acl_entry *entry;
	unsigned int id;

	if (!nfsacl_desc->acl) {
		if (desc->array_len > NFS_ACL_MAX_ENTRIES)
			return -EINVAL;
		nfsacl_desc->acl = posix_acl_alloc(desc->array_len, GFP_KERNEL);
		if (!nfsacl_desc->acl)
			return -ENOMEM;
		nfsacl_desc->count = 0;
	}

	entry = &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
	entry->e_tag = ntohl(*p++) & ~NFS_ACL_DEFAULT;
	id = ntohl(*p++);
	entry->e_perm = ntohl(*p++);

	switch(entry->e_tag) {
		case ACL_USER:
			entry->e_uid = make_kuid(&init_user_ns, id);
			if (!uid_valid(entry->e_uid))
				return -EINVAL;
			break;
		case ACL_GROUP:
			entry->e_gid = make_kgid(&init_user_ns, id);
			if (!gid_valid(entry->e_gid))
				return -EINVAL;
			break;
		case ACL_USER_OBJ:
		case ACL_GROUP_OBJ:
		case ACL_OTHER:
			if (entry->e_perm & ~S_IRWXO)
				return -EINVAL;
			break;
		case ACL_MASK:
			/* Solaris sometimes sets additional bits in the mask */
			entry->e_perm &= S_IRWXO;
			break;
		default:
			return -EINVAL;
	}

	return 0;
}

static int
cmp_acl_entry(const void *x, const void *y)
{
	const struct posix_acl_entry *a = x, *b = y;

	if (a->e_tag != b->e_tag)
		return a->e_tag - b->e_tag;
	else if ((a->e_tag == ACL_USER) && uid_gt(a->e_uid, b->e_uid))
		return 1;
	else if ((a->e_tag == ACL_USER) && uid_lt(a->e_uid, b->e_uid))
		return -1;
	else if ((a->e_tag == ACL_GROUP) && gid_gt(a->e_gid, b->e_gid))
		return 1;
	else if ((a->e_tag == ACL_GROUP) && gid_lt(a->e_gid, b->e_gid))
		return -1;
	else
		return 0;
}

/*
 * Convert from a Solaris ACL to a POSIX 1003.1e draft 17 ACL.
 */
static int
posix_acl_from_nfsacl(struct posix_acl *acl)
{
	struct posix_acl_entry *pa, *pe,
	       *group_obj = NULL, *mask = NULL;

	if (!acl)
		return 0;

	sort(acl->a_entries, acl->a_count, sizeof(struct posix_acl_entry),
	     cmp_acl_entry, NULL);

	/* Find the ACL_GROUP_OBJ and ACL_MASK entries. */
	FOREACH_ACL_ENTRY(pa, acl, pe) {
		switch(pa->e_tag) {
			case ACL_USER_OBJ:
				break;
			case ACL_GROUP_OBJ:
				group_obj = pa;
				break;
			case ACL_MASK:
				mask = pa;
				fallthrough;
			case ACL_OTHER:
				break;
		}
	}
	if (acl->a_count == 4 && group_obj && mask &&
	    mask->e_perm == group_obj->e_perm) {
		/* remove bogus ACL_MASK entry */
		memmove(mask, mask+1, (3 - (mask - acl->a_entries)) *
				      sizeof(struct posix_acl_entry));
		acl->a_count = 3;
	}
	return 0;
}

/**
 * nfsacl_decode - Decode an NFSv3 ACL
 *
 * @buf: xdr_buf containing XDR'd ACL data to decode
 * @base: byte offset in xdr_buf where XDR'd ACL begins
 * @aclcnt: count of ACEs in decoded posix_acl
 * @pacl: buffer in which to place decoded posix_acl
 *
 * Returns the length of the decoded ACL in bytes, or a negative errno value.
 */
int nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt,
		  struct posix_acl **pacl)
{
	struct nfsacl_decode_desc nfsacl_desc = {
		.desc = {
			.elem_size = 12,
			.xcode = pacl ? xdr_nfsace_decode : NULL,
		},
	};
	u32 entries;
	int err;

	if (xdr_decode_word(buf, base, &entries) ||
	    entries > NFS_ACL_MAX_ENTRIES)
		return -EINVAL;
	nfsacl_desc.desc.array_maxlen = entries;
	err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc);
	if (err)
		return err;
	if (pacl) {
		if (entries != nfsacl_desc.desc.array_len ||
		    posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
			posix_acl_release(nfsacl_desc.acl);
			return -EINVAL;
		}
		*pacl = nfsacl_desc.acl;
	}
	if (aclcnt)
		*aclcnt = entries;
	return 8 + nfsacl_desc.desc.elem_size *
		   nfsacl_desc.desc.array_len;
}
EXPORT_SYMBOL_GPL(nfsacl_decode);

/**
 * nfs_stream_decode_acl - Decode an NFSv3 ACL
 *
 * @xdr: an xdr_stream positioned at an encoded ACL
 * @aclcnt: OUT: count of ACEs in decoded posix_acl
 * @pacl: OUT: a dynamically-allocated buffer containing the decoded posix_acl
 *
 * Return values:
 *   %false: The encoded ACL is not valid
 *   %true: @pacl contains a decoded ACL, and @xdr is advanced
 *
 * On a successful return, caller must release *pacl using posix_acl_release().
 */
bool nfs_stream_decode_acl(struct xdr_stream *xdr, unsigned int *aclcnt,
			   struct posix_acl **pacl)
{
	const size_t elem_size = XDR_UNIT * 3;
	struct nfsacl_decode_desc nfsacl_desc = {
		.desc = {
			.elem_size = elem_size,
			.xcode = pacl ? xdr_nfsace_decode : NULL,
		},
	};
	unsigned int base;
	u32 entries;

	if (xdr_stream_decode_u32(xdr, &entries) < 0)
		return false;
	if (entries > NFS_ACL_MAX_ENTRIES)
		return false;

	base = xdr_stream_pos(xdr);
	if (!xdr_inline_decode(xdr, XDR_UNIT + elem_size * entries))
		return false;
	nfsacl_desc.desc.array_maxlen = entries;
	if (xdr_decode_array2(xdr->buf, base, &nfsacl_desc.desc))
		return false;

	if (pacl) {
		if (entries != nfsacl_desc.desc.array_len ||
		    posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
			posix_acl_release(nfsacl_desc.acl);
			return false;
		}
		*pacl = nfsacl_desc.acl;
	}
	if (aclcnt)
		*aclcnt = entries;
	return true;
}
EXPORT_SYMBOL_GPL(nfs_stream_decode_acl);
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0-only
	2	/*
	3	* fs/nfs_common/nfsacl.c
	4	*
	5	* Copyright (C) 2002-2003 Andreas Gruenbacher <agruen@suse.de>
	6	*/
	7
	8	/*
	9	* The Solaris nfsacl protocol represents some ACLs slightly differently
	10	* than POSIX 1003.1e draft 17 does (and we do):
	11	*
	12	* - Minimal ACLs always have an ACL_MASK entry, so they have
	13	* four instead of three entries.
	14	* - The ACL_MASK entry in such minimal ACLs always has the same
	15	* permissions as the ACL_GROUP_OBJ entry. (In extended ACLs
	16	* the ACL_MASK and ACL_GROUP_OBJ entries may differ.)
	17	* - The identifier fields of the ACL_USER_OBJ and ACL_GROUP_OBJ
	18	* entries contain the identifiers of the owner and owning group.
	19	* (In POSIX ACLs we always set them to ACL_UNDEFINED_ID).
	20	* - ACL entries in the kernel are kept sorted in ascending order
	21	* of (e_tag, e_id). Solaris ACLs are unsorted.
	22	*/
	23
	24	#include <linux/module.h>
	25	#include <linux/fs.h>
	26	#include <linux/gfp.h>
	27	#include <linux/sunrpc/xdr.h>
	28	#include <linux/nfsacl.h>
	29	#include <linux/nfs3.h>
	30	#include <linux/sort.h>
	31
	32	MODULE_DESCRIPTION("NFS ACL support");
	33	MODULE_LICENSE("GPL");
	34
	35	struct nfsacl_encode_desc {
	36	struct xdr_array2_desc desc;
	37	unsigned int count;
	38	struct posix_acl *acl;
	39	int typeflag;
	40	kuid_t uid;
	41	kgid_t gid;
	42	};
	43
	44	struct nfsacl_simple_acl {
	45	struct posix_acl_hdr acl;
	46	struct posix_acl_entry ace[4];
	47	};
	48
	49	static int
	50	xdr_nfsace_encode(struct xdr_array2_desc desc, void elem)
	51	{
	52	struct nfsacl_encode_desc *nfsacl_desc =
	53	(struct nfsacl_encode_desc *) desc;
	54	__be32 *p = elem;
	55
	56	struct posix_acl_entry *entry =
	57	&nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
	58
	59	*p++ = htonl(entry->e_tag \| nfsacl_desc->typeflag);
	60	switch(entry->e_tag) {
	61	case ACL_USER_OBJ:
	62	*p++ = htonl(from_kuid(&init_user_ns, nfsacl_desc->uid));
	63	break;
	64	case ACL_GROUP_OBJ:
	65	*p++ = htonl(from_kgid(&init_user_ns, nfsacl_desc->gid));
	66	break;
	67	case ACL_USER:
	68	*p++ = htonl(from_kuid(&init_user_ns, entry->e_uid));
	69	break;
	70	case ACL_GROUP:
	71	*p++ = htonl(from_kgid(&init_user_ns, entry->e_gid));
	72	break;
	73	default: /* Solaris depends on that! */
	74	*p++ = 0;
	75	break;
	76	}
	77	*p++ = htonl(entry->e_perm & S_IRWXO);
	78	return 0;
	79	}
	80
	81	/**
	82	* nfsacl_encode - Encode an NFSv3 ACL
	83	*
	84	* @buf: destination xdr_buf to contain XDR encoded ACL
	85	* @base: byte offset in xdr_buf where XDR'd ACL begins
	86	* @inode: inode of file whose ACL this is
	87	* @acl: posix_acl to encode
	88	* @encode_entries: whether to encode ACEs as well
	89	* @typeflag: ACL type: NFS_ACL_DEFAULT or zero
	90	*
	91	* Returns size of encoded ACL in bytes or a negative errno value.
	92	*/
	93	int nfsacl_encode(struct xdr_buf buf, unsigned int base, struct inode inode,
	94	struct posix_acl *acl, int encode_entries, int typeflag)
	95	{
	96	int entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
	97	struct nfsacl_encode_desc nfsacl_desc = {
	98	.desc = {
	99	.elem_size = 12,
	100	.array_len = encode_entries ? entries : 0,
	101	.xcode = xdr_nfsace_encode,
	102	},
	103	.acl = acl,
	104	.typeflag = typeflag,
	105	.uid = inode->i_uid,
	106	.gid = inode->i_gid,
	107	};
	108	struct nfsacl_simple_acl aclbuf;
	109	int err;
	110
	111	if (entries > NFS_ACL_MAX_ENTRIES \|\|
	112	xdr_encode_word(buf, base, entries))
	113	return -EINVAL;
	114	if (encode_entries && acl && acl->a_count == 3) {
	115	struct posix_acl *acl2 =
	116	container_of(&aclbuf.acl, struct posix_acl, hdr);
	117
	118	/* Avoid the use of posix_acl_alloc(). nfsacl_encode() is
	119	* invoked in contexts where a memory allocation failure is
	120	* fatal. Fortunately this fake ACL is small enough to
	121	* construct on the stack. */
	122	posix_acl_init(acl2, 4);
	123
	124	/* Insert entries in canonical order: other orders seem
	125	to confuse Solaris VxFS. */
	126	acl2->a_entries[0] = acl->a_entries[0]; /* ACL_USER_OBJ */
	127	acl2->a_entries[1] = acl->a_entries[1]; /* ACL_GROUP_OBJ */
	128	acl2->a_entries[2] = acl->a_entries[1]; /* ACL_MASK */
	129	acl2->a_entries[2].e_tag = ACL_MASK;
	130	acl2->a_entries[3] = acl->a_entries[2]; /* ACL_OTHER */
	131	nfsacl_desc.acl = acl2;
	132	}
	133	err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc);
	134	if (!err)
	135	err = 8 + nfsacl_desc.desc.elem_size *
	136	nfsacl_desc.desc.array_len;
	137	return err;
	138	}
	139	EXPORT_SYMBOL_GPL(nfsacl_encode);
	140
	141	/**
	142	* nfs_stream_encode_acl - Encode an NFSv3 ACL
	143	*
	144	* @xdr: an xdr_stream positioned to receive an encoded ACL
	145	* @inode: inode of file whose ACL this is
	146	* @acl: posix_acl to encode
	147	* @encode_entries: whether to encode ACEs as well
	148	* @typeflag: ACL type: NFS_ACL_DEFAULT or zero
	149	*
	150	* Return values:
	151	* %false: The ACL could not be encoded
	152	* %true: @xdr is advanced to the next available position
	153	*/
	154	bool nfs_stream_encode_acl(struct xdr_stream xdr, struct inode inode,
	155	struct posix_acl *acl, int encode_entries,
	156	int typeflag)
	157	{
	158	const size_t elem_size = XDR_UNIT * 3;
	159	u32 entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
	160	struct nfsacl_encode_desc nfsacl_desc = {
	161	.desc = {
	162	.elem_size = elem_size,
	163	.array_len = encode_entries ? entries : 0,
	164	.xcode = xdr_nfsace_encode,
	165	},
	166	.acl = acl,
	167	.typeflag = typeflag,
	168	.uid = inode->i_uid,
	169	.gid = inode->i_gid,
	170	};
	171	struct nfsacl_simple_acl aclbuf;
	172	unsigned int base;
	173	int err;
	174
	175	if (entries > NFS_ACL_MAX_ENTRIES)
	176	return false;
	177	if (xdr_stream_encode_u32(xdr, entries) < 0)
	178	return false;
	179
	180	if (encode_entries && acl && acl->a_count == 3) {
	181	struct posix_acl *acl2 =
	182	container_of(&aclbuf.acl, struct posix_acl, hdr);
	183
	184	/* Avoid the use of posix_acl_alloc(). nfsacl_encode() is
	185	* invoked in contexts where a memory allocation failure is
	186	* fatal. Fortunately this fake ACL is small enough to
	187	* construct on the stack. */
	188	posix_acl_init(acl2, 4);
	189
	190	/* Insert entries in canonical order: other orders seem
	191	to confuse Solaris VxFS. */
	192	acl2->a_entries[0] = acl->a_entries[0]; /* ACL_USER_OBJ */
	193	acl2->a_entries[1] = acl->a_entries[1]; /* ACL_GROUP_OBJ */
	194	acl2->a_entries[2] = acl->a_entries[1]; /* ACL_MASK */
	195	acl2->a_entries[2].e_tag = ACL_MASK;
	196	acl2->a_entries[3] = acl->a_entries[2]; /* ACL_OTHER */
	197	nfsacl_desc.acl = acl2;
	198	}
	199
	200	base = xdr_stream_pos(xdr);
	201	if (!xdr_reserve_space(xdr, XDR_UNIT +
	202	elem_size * nfsacl_desc.desc.array_len))
	203	return false;
	204	err = xdr_encode_array2(xdr->buf, base, &nfsacl_desc.desc);
	205	if (err)
	206	return false;
	207
	208	return true;
	209	}
	210	EXPORT_SYMBOL_GPL(nfs_stream_encode_acl);
	211
	212
	213	struct nfsacl_decode_desc {
	214	struct xdr_array2_desc desc;
	215	unsigned int count;
	216	struct posix_acl *acl;
	217	};
	218
	219	static int
	220	xdr_nfsace_decode(struct xdr_array2_desc desc, void elem)
	221	{
	222	struct nfsacl_decode_desc *nfsacl_desc =
	223	(struct nfsacl_decode_desc *) desc;
	224	__be32 *p = elem;
	225	struct posix_acl_entry *entry;
	226	unsigned int id;
	227
	228	if (!nfsacl_desc->acl) {
	229	if (desc->array_len > NFS_ACL_MAX_ENTRIES)
	230	return -EINVAL;
	231	nfsacl_desc->acl = posix_acl_alloc(desc->array_len, GFP_KERNEL);
	232	if (!nfsacl_desc->acl)
	233	return -ENOMEM;
	234	nfsacl_desc->count = 0;
	235	}
	236
	237	entry = &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
	238	entry->e_tag = ntohl(*p++) & ~NFS_ACL_DEFAULT;
	239	id = ntohl(*p++);
	240	entry->e_perm = ntohl(*p++);
	241
	242	switch(entry->e_tag) {
	243	case ACL_USER:
	244	entry->e_uid = make_kuid(&init_user_ns, id);
	245	if (!uid_valid(entry->e_uid))
	246	return -EINVAL;
	247	break;
	248	case ACL_GROUP:
	249	entry->e_gid = make_kgid(&init_user_ns, id);
	250	if (!gid_valid(entry->e_gid))
	251	return -EINVAL;
	252	break;
	253	case ACL_USER_OBJ:
	254	case ACL_GROUP_OBJ:
	255	case ACL_OTHER:
	256	if (entry->e_perm & ~S_IRWXO)
	257	return -EINVAL;
	258	break;
	259	case ACL_MASK:
	260	/* Solaris sometimes sets additional bits in the mask */
	261	entry->e_perm &= S_IRWXO;
	262	break;
	263	default:
	264	return -EINVAL;
	265	}
	266
	267	return 0;
	268	}
	269
	270	static int
	271	cmp_acl_entry(const void x, const void y)
	272	{
	273	const struct posix_acl_entry a = x, b = y;
	274
	275	if (a->e_tag != b->e_tag)
	276	return a->e_tag - b->e_tag;
	277	else if ((a->e_tag == ACL_USER) && uid_gt(a->e_uid, b->e_uid))
	278	return 1;
	279	else if ((a->e_tag == ACL_USER) && uid_lt(a->e_uid, b->e_uid))
	280	return -1;
	281	else if ((a->e_tag == ACL_GROUP) && gid_gt(a->e_gid, b->e_gid))
	282	return 1;
	283	else if ((a->e_tag == ACL_GROUP) && gid_lt(a->e_gid, b->e_gid))
	284	return -1;
	285	else
	286	return 0;
	287	}
	288
	289	/*
	290	* Convert from a Solaris ACL to a POSIX 1003.1e draft 17 ACL.
	291	*/
	292	static int
	293	posix_acl_from_nfsacl(struct posix_acl *acl)
	294	{
	295	struct posix_acl_entry pa, pe,
	296	group_obj = NULL, mask = NULL;
	297
	298	if (!acl)
	299	return 0;
	300
	301	sort(acl->a_entries, acl->a_count, sizeof(struct posix_acl_entry),
	302	cmp_acl_entry, NULL);
	303
	304	/* Find the ACL_GROUP_OBJ and ACL_MASK entries. */
	305	FOREACH_ACL_ENTRY(pa, acl, pe) {
	306	switch(pa->e_tag) {
	307	case ACL_USER_OBJ:
	308	break;
	309	case ACL_GROUP_OBJ:
	310	group_obj = pa;
	311	break;
	312	case ACL_MASK:
	313	mask = pa;
	314	fallthrough;
	315	case ACL_OTHER:
	316	break;
	317	}
	318	}
	319	if (acl->a_count == 4 && group_obj && mask &&
	320	mask->e_perm == group_obj->e_perm) {
	321	/* remove bogus ACL_MASK entry */
	322	memmove(mask, mask+1, (3 - (mask - acl->a_entries)) *
	323	sizeof(struct posix_acl_entry));
	324	acl->a_count = 3;
	325	}
	326	return 0;
	327	}
	328
	329	/**
	330	* nfsacl_decode - Decode an NFSv3 ACL
	331	*
	332	* @buf: xdr_buf containing XDR'd ACL data to decode
	333	* @base: byte offset in xdr_buf where XDR'd ACL begins
	334	* @aclcnt: count of ACEs in decoded posix_acl
	335	* @pacl: buffer in which to place decoded posix_acl
	336	*
	337	* Returns the length of the decoded ACL in bytes, or a negative errno value.
	338	*/
	339	int nfsacl_decode(struct xdr_buf buf, unsigned int base, unsigned int aclcnt,
	340	struct posix_acl **pacl)
	341	{
	342	struct nfsacl_decode_desc nfsacl_desc = {
	343	.desc = {
	344	.elem_size = 12,
	345	.xcode = pacl ? xdr_nfsace_decode : NULL,
	346	},
	347	};
	348	u32 entries;
	349	int err;
	350
	351	if (xdr_decode_word(buf, base, &entries) \|\|
	352	entries > NFS_ACL_MAX_ENTRIES)
	353	return -EINVAL;
	354	nfsacl_desc.desc.array_maxlen = entries;
	355	err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc);
	356	if (err)
	357	return err;
	358	if (pacl) {
	359	if (entries != nfsacl_desc.desc.array_len \|\|
	360	posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
	361	posix_acl_release(nfsacl_desc.acl);
	362	return -EINVAL;
	363	}
	364	*pacl = nfsacl_desc.acl;
	365	}
	366	if (aclcnt)
	367	*aclcnt = entries;
	368	return 8 + nfsacl_desc.desc.elem_size *
	369	nfsacl_desc.desc.array_len;
	370	}
	371	EXPORT_SYMBOL_GPL(nfsacl_decode);
	372
	373	/**
	374	* nfs_stream_decode_acl - Decode an NFSv3 ACL
	375	*
	376	* @xdr: an xdr_stream positioned at an encoded ACL
	377	* @aclcnt: OUT: count of ACEs in decoded posix_acl
	378	* @pacl: OUT: a dynamically-allocated buffer containing the decoded posix_acl
	379	*
	380	* Return values:
	381	* %false: The encoded ACL is not valid
	382	* %true: @pacl contains a decoded ACL, and @xdr is advanced
	383	*
	384	* On a successful return, caller must release *pacl using posix_acl_release().
	385	*/
	386	bool nfs_stream_decode_acl(struct xdr_stream xdr, unsigned int aclcnt,
	387	struct posix_acl **pacl)
	388	{
	389	const size_t elem_size = XDR_UNIT * 3;
	390	struct nfsacl_decode_desc nfsacl_desc = {
	391	.desc = {
	392	.elem_size = elem_size,
	393	.xcode = pacl ? xdr_nfsace_decode : NULL,
	394	},
	395	};
	396	unsigned int base;
	397	u32 entries;
	398
	399	if (xdr_stream_decode_u32(xdr, &entries) < 0)
	400	return false;
	401	if (entries > NFS_ACL_MAX_ENTRIES)
	402	return false;
	403
	404	base = xdr_stream_pos(xdr);
	405	if (!xdr_inline_decode(xdr, XDR_UNIT + elem_size * entries))
	406	return false;
	407	nfsacl_desc.desc.array_maxlen = entries;
	408	if (xdr_decode_array2(xdr->buf, base, &nfsacl_desc.desc))
	409	return false;
	410
	411	if (pacl) {
	412	if (entries != nfsacl_desc.desc.array_len \|\|
	413	posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
	414	posix_acl_release(nfsacl_desc.acl);
	415	return false;
	416	}
	417	*pacl = nfsacl_desc.acl;
	418	}
	419	if (aclcnt)
	420	*aclcnt = entries;
	421	return true;
	422	}
	423	EXPORT_SYMBOL_GPL(nfs_stream_decode_acl);